1. Field of the Invention
This invention generally relates to occupant safety during a collision, and more specifically to a “customized” or “tunable” energy absorber that absorbs energy imparted by an incident object that impacts the absorber, and a method for configuring the absorber.
2. Background Art
The National Highway Traffic and Safety Administration has been asked by Congress to improve protection for vehicle occupants, especially children, in side-impact crashes. Side collisions can be particularly deadly for infants, even if they are strapped in child seats. About 40% of children who died strapped in such seats were killed in side-impact crashes, according to one analysis of almost 100 fatal crashes by the Insurance Institute for Highway Safety. A study by the Childrenh's National and Medical Center in 2000 found that the side door panel was the primary source of contact for injuries suffered in lateral crashes. Other studies have suggested that an evaluation of the side-impact protection afforded by primary source of contact for injuries suffered in lateral crashes. Other studies have suggested that an evaluation of the side-impact protection afforded by automobiles should contemplate ways in which to preserve the occupant's space during a lateral collision to better protect all occupants.
There have been proposed various ways to protect the occupant or rider of an automobile when the occupant impacts the A and B pillars, headliner, or any hard structure during an impact. Illustrative approaches are described in commonly owned U.S. Pat. Nos. 6,247,745; 6,199,942; 6,679,967; 6,682,128; 6,752,450; and 6,443,513, which issued on Sep. 3, 2002 to Glance.
It is known, for example, to deploy truncated plastic cones at rollover stiff points or on door panels for side impacts with the objective of providing better performance than energy absorbent foam. Also, such cones may be less expensive to manufacture. Manufacturing economics have been realized from the raw materials being melt recyclable. Such structures not only provide weight savings and a better performance, but also a cost advantage which may amount to $4-$5 per vehicle.
Some of the required energy absorption characteristics are defined in Federal Motor Vehicle Standards 201. To meet the relevant standards, the industry continues its quest not only for the physical structures that conform to federally mandated standards, but also to develop computer modeling protocols that predict head injury sustained from impacting forces and comparing the results with head injury criteria. It would be desirable in such developments to measure actual head impact (of, for example, a dummy occupant) during in-vehicle testing at selected locations in the vehicle. Ideally, the actual measurements will approximate the values predicted by computer dynamic finite element analysis.
Additionally, the desire to reduce costs while complying with End of Life Vehicle (ELV) legislation in Europe stimulates the use of mono-materials in automotive interior soft trim applications. Related considerations emphasize the recyclability of automotive plastics. The impact or influence of the ELV directive on automotive interiors will be felt in various ways: e.g., cost effective use of recycling techniques with environmentally benign consequences. Most interior modules today are made from a combination of skin/foam/substrate. Thus, the materials currently used may present challenges to the recycling task. Such challenges may be met by more use of energy absorbing modules that are made from mono-materials. Such materials might, for example, include polyolefins and melt recyclable polymers, since they show promise as being versatile alternatives to skin/foam/substrate.
It is expected that Europe will adopt the U.S. HIC(d) requirements. This will affect the choice and quantity of materials used for energy absorbers in headliners. Similar door trim panel requirements apply to the pelvis and torso (side impact applications). It is therefore anticipated that there will be an increase in the usage of energy absorbers that will be incorporated into the structure of modules such as door trim panels, instrument panel uppers, and headliners.
To meet cost reduction goals, there is an increasing desire to manufacture interior modules using a reduced number of manufacturing steps.
In light of these and related approaches, there remains the desire to absorb as much impact energy in as little crush distance as possible, with as little weight as possible, yet be capable of being designed and manufactured under favorable economic conditions.
The absorber may, for example, be positioned in a vehicle headliner, in an A-pillar, B-pillar, or in other locations. Generally, the energy absorber is positioned between a vehicle occupant and an incident force. It serves to at least partially cushion a blow and thus protect the occupant from severe injury.